Floating dry-dock.



W. T. DONNELLY.

FLOATING DRY DOCK.

APPLICATION IILED JAN. 3, 190a.

920,282. Patented May 4, 1909.

2 SHEETS-SHEET 1.

furs "on! PETERS no, wuzsrwnlcmu, 0. c4

W. T. DONNELLY. V FLOATING DRY DOCK.

APPLICATION FILED JAN. 3, 1908.

920,282, Patented May 4, 1909.

2 SHEETS-SHEET 2.

o o o c Q o (a H a b] a a Ea fix m o swugnkoz WILLIAM THOMAS DONNELLY,OF BROOKLYN, NEW YORK.

FLOATING DRY-DOCK.

Specification of Letters Patent.

Patented May 4, 1909.

Application filed January 3, 1908. Serial No. 409,178.

To all whom it an (my concern:

Be it known that I, \VILLIAM THOMAS DONNELLY, a citizen of the UnitedStates, residing at Brooklyn, in the county of Kings and State of NewYork, have invented certain new and useful Improvements in FloatingDry-Docks, of which the following is a specification.

My invention relates to improvements in floating dry docks and moreespecially to a floatin dry dock having wooden pontoons and 110 lowmetal wings or sides.

It has for its objects to provide a floating dry dock which isfireproof, durable, strong and rigid, unsinkable, self docking, and notaffected by atmospheric or temperature changes and which has a maximumamount of lifting power for a given size or dimensions of the pontoons.

From time to time attempts have been made to build composite structuresfor floating dry docks, that is, with steel framing or trusses coveredwith wood but all these attempts have been unsuccessful andunsatisfactory as it is very diflicu it to so connect the steel and woodas to give each the proper strength and at the same time obtain asullicient or adequate bearing surface between the Wood and steel.

By my invention I do not attempt a composite structure but a combinedstructure, that is, all those parts of the structure which support theweigl'it of the ship, viz., the pontoons, are made entirely of wood andthe wings or sides, which perform an entirely different function andhave no part in supporting the weight of the ship, but simply connectthe pontoons together, maintain the stability while the dock is beingraised and lowered and provide longitudinal rigidity in the structure asa whole I make entirely of steel and each of these materials isespecially adapted for the purpose for which it is used and theresultant dock is far superior to a dock built wholly of either wood orsteel.

Vith Wood as a structural material it has been found impracticable toconstruct a floating dry dock with continuous side walls or wings of agreater length than. three hundred feet but with steel as a structuralmaterial for the wings it is entirely practical and feasible to extendthe length of floating dry docks with continuous side walls or wings toany desired length. In a floating dry dock with steel side walls orwings and wooden pontoons the weight of the steel sides or wings is onlyjust suflicient to sink the entire structure, when all the pontoons andthe side walls are flooded, consequently the total submergence of thedock is highly improbable as a reserve bouyancy in any one or two of thepontoons would prevent the sinking of the dock. In case of injury to oneof the wooden pontoons of this dock and its complete flooding with waterit will upon detachment from the steel side walls or wings continue tofloat whereas a steel pontoon under the same conditions could not behandled without supplementary floats or other wrecking appliances.

In all timber floating dry docks it is necessary to sacrifice a largeamount of lifting power on account of the ballast required to sink thedock after water has been allowed to enter it. As the timber availablefor building these docks, including the fastenings and pumping machineryfor the same, does not have a greater weight than 46 pounds per cubicfoot and the weight of sea water is 64 pounds per cubic foot, it isnecessary to add in ballast for every cubic foot of lumber used thedifference, or 18 pounds, and as a cubic foot of lumber contains 12board feet this amounts to one ound and a half of ballast per board footof umber used. A live thousand ton floating dry dock will requireapproximately one and one half million board feet of lumber consequentlyrequiring two million two hundred and fifty thousand pounds of ballast,or one thousand one hundred and twenty live tons. The commercial cost ofthis ballast necessitates the use of stone and as it is not possible toobtain. stone of a greater specific gravity than two hundred pounds percubic foot and as the ballast is submerged. there is a loss of 64 poundsper cubic foot due to its displacement and this necessitates theincrease of the stone ballast in proportion to the relation of itsspecific gravity to its weight, that is, to obtain one thousand onehundred and twenty flve tons of effective ballast it is necessary to use1650 tons of stone. This means that a timber floating dry dock to have anet lifting power of five thousand tons must be increased in dimensionsso as to provide for supporting 1650 tons of stone as well as the weightof the ship when pumped out. By the use of steel wings or sides andwooden pontoons the wings act as ballast sinkers for the wood of thepontoons and by this means I obtain an increase in lifting power withthe same dimension of pontoons of about 1650 tons.

Wood exposed to the atmosphere and moisture and temperature changes,rapidly deteriorates and when the wings are in one structure or piecewith. the pontoons or lifting power it is difficult to replace them orkeep them in proper repair, on the other hand when the Wings are builtof steel and are not subjected to the action of salt water,

except for a short time while the dock is lowered or submerged, there islittle or no difficulty experienced in so protecting them that the wholestructure Will have an indeterminate or long life, and in fact with apontoon and wing dock constructed of separate pieces as herein shown itis possible at any time to wholly replace a pontoon or wing, and in adeck of a lifting capacity of five thousand tons for less than ten percent. of the original cost of the dock, and as this could be done fromtime to time the integrity of the structure as a whole will always bemaintained.

A dock with steel wings and wooden pontoons is fireproof as the steelwings cannot burn, and the wooden pontoons being submerged in the watercannot burn.

Referring to the drawings: Figure 1, is an end view in elevation, partlyin section, Fig. 2, a top plan view, Fig. ,3, a top plan view of theframe which is placed between the bottom of the wings and the top of thepontoons.

' in the drawings in which like numerals of reference denote like partsthroughout the several views, 1, represents the floating dry dock, whichas shown is composed of a series of 9 wooden pontoons 2, but which maycomprise a greater or less number, as may be found necessary to meet thedifferent requirements. Sides or wings 3, made of steel or othersuitable metal, and which are hollou and made water and air tight, aremounted on the series of pontoons and secured thereto by suitable bolts4. The pontoons are designed to be provided with the usual keelblocks,bilge-blocks, water inlets and outlets, and other parts necessary forthe'operation of the dock, which are not shown as they form no part ofthe invention.

A rectangular frame 5, is mounted between the top of each pontoon andthe bottom of the sides or wings, which provides an air and water tightconnection, and at substantially its central portion is provided withtransverse strios or partitions 6 and 7, between which a closed chamberor compartment 8,

. is formed.

The top of each pontoon is provided with an aperture 9, and the bottomof the wings are provided with a series of apertures 10, in alinementwith the apertures 9, said apertures and the chamber 8, furnishingcommunication between the pontoons and the wings.

The shape and size of both the wings or sides and the pontoons may bevaried to meet the different requirements found necessary to adapt thedock to the use for which it is to be constructed.

1 do not desire to be understood as limiting myself to the specificdetails of construction and arrangement'as herein described andillustrated, as it is manifest that variations and modifications may bemade in the features of construction and arrangement in the adaptationof the device to various conditions of use without departing from thespirit and scope of my invention and irnmoverents. I therefore reservethe right to all such variations and modifications as properl fallwithin the scone of m invention and J I r the terms of the followingclaims.

il hat I claim is:-

1. in a floating dry-dock, a series of porn toons buoyant when filledwith water, sides or wings supported thereon non-buoyant when filledwith water and passages establishing communication between said pontoonsand sides or wings, whereby water is admitted to and exhausted from thesides or n ings through the pontoons, substantially described.

2. in a floating dry-dock, a series of pontoons buoyant when filled withwater, sides or wings supported thereon non-buoyant when filled v. thwater and registering apertures establishing communication between saidpontoons and said sides or wings, whereby water is admitted to andexhausted from the sides or wings through the pontoons, substantially asdescribed.

8. In a floating dry-dock, a series of pontoons buoyant when filled withwater, sides or wings supported thereon non-buoyant when filled withwater and means establish ing coninninication between said pontoons andsides or wings, whereby water is admitted to and exhausted from thesides or wings through the pontoons, substantially as described.

in testimony whereof have signed my name in the presence of'twosubscribing witnosses.

WlLLlAlvl THOMAS llONNllliliY.

l'l itnesses lanes W. McELnrNNnY, WILLIAM J. CAMPBELL.

